THURSDAY, Dec. 4, 2003 (HealthDayNews) -- Red wine may do more than reduce the risk of heart disease. The grape skin and seeds appear to hold a natural cancer-fighting chemical, California researchers report.
Scientists at City of Hope Cancer Center in Los Angeles isolated a phytochemical, called procyanidin B dimer, that when given to mice with breast cancer reduced the size of their tumors.
While there are already drugs on the market that can control estrogen-dependent breast cancer development in post-menopausal women, this is the first naturally occurring phytochemical that appears to have the same effect, says study author Shiuan Chen.
"It was surprising that we were able to identify this chemical in a natural source," says Chen, director of surgical research at City of Hope. "Further, there was a pretty significant reduction of tumor size in all the mice, and a number of animals ended up with no tumors."
However, Chen says that natural phytochemicals are more likely to be used in a preventive way than as treatment for breast cancer because existing drugs are far stronger.
"We are talking about prevention," he says. "By having this in the diet, one can keep the estrogen at a lower level, which can be preventive for breast cancer."
For post-menopausal women who have breast cancer tumors that are fed by estrogen, which make up about 75 percent of breast cancers in this age group, estrogen-suppressing therapy is aimed at the estrogen produced outside of the ovaries, in peripheral tissue like fat and skin cells, Chen says.
New drugs like anastrozole, letrozole and exemestane, which are taken in pill form, work by reducing the activity of an enzyme called aromatase that is key to the production of estrogen. The estrogen is no longer available to breast cancer tumors, inhibiting their growth.
The phytochemicals work in the same way as these drugs, but have the advantage of naturally occurring in grape skins and seeds, Chen says.
The study was published this week in the journal Cancer Research.
Chen cautions that the research is based on an animal study, and that clinical trials on post-menopausal women are needed to confirm any benefit to humans. He says he's conducting such trials now.
"We have to be careful," he adds. "We don't support the idea of people drinking a lot of red wine, as alcohol is a risk factor for breast cancer."
For instance, he notes, that for women to ingest the comparable amount of procyanidin B dimer given to the mice, they'd have to drink a half bottle of red wine daily.
But he adds, for normal, healthy women, a glass of red wine a day or eating grapes with skins and seeds may just reduce the overall circulation of estrogen in the body.
Why does red wine confer this potential benefit and white wine doesn't?
Chen says red wine is made by fermenting not just the juice from a wine grape, but the skin and seeds as well, which is where the phytochemical is located. White wine is most often made by using just the juice from the grape and discarding the skin and seeds, he says.
Tom Klassen, assistant winemaker of Landmark Vineyards in Kenwood, Calif., says, "The general tendency is that red wines get fermented with skins and seeds, and white wines do not. Red wines will spend a week with skins and seeds, and sometimes much longer -- they may be on the skins for a month or more."
Dr. Jay Brooks, chief of hematology/oncology at the Ochsner Clinic Foundation in Baton Rouge, La., calls the new research "very interesting work that shows that many of the foodstuffs we eat have beneficial effects.
"A lot of epidemiologic studies show that a glass of red wine may be beneficial for reducing heart disease," he says. He adds that, despite the studies showing alcohol consumption is a risk factor for breast cancer, "if a woman drinks a glass of red wine per day, it will not increase her risk of breast cancer dramatically."
More information
For news on the efficacy of aromatase-inhibiting drugs in treating breast cancer, visit the National Institutes of Health. The American Cancer Society reports on the risks of under-treating elderly women with breast cancer.
